Booster pump for pipe lining apparatus



July 17, 1962 A. J. PERKINS ETAL 3,044,407

BOOSTER PUMP FOR PIPE LINING APPARATUS Filed Aug. 16, 1960 3,044,406Patented July 17, 1962 ELECTROMOTOR-DRIVEN CENTRlFU GAL PUMP Nils HenryBiirje Kristenson, Stockholm, Sweden, as-

signor to Scandinavian Agencies Corp. Ltd., Tangier,

Morocco Filed June 6, 1960, Ser. No. 33,967 1 Claims priority,application Sweden July 22, 1959 4 Claims. (Cl. 103-87) The inventionrelates to electromotor-driven centrifugal pumps, particularly bilgepumps, of the kind in which the drive motor is cooled by the liquidbeing pumped, said liquid being allowed to pass through a duct system inheat-transferring relation to the motor and comprising, most commonly,one single cooling duct which is annular in cross section and isconfined between the motor and an outer casing surrounding the latter.

If for some reason or other the pumping unit of such electromotor-drivencentrifugal pumps should cease to force liquid through the cooling ductsystem, due, for instance, to the pump having drained off the body ofwater in which it is immersed, this will interrupt the cooling of themotor. Even though the latter will now be idling, thus reducing thedevelopment of heat therein, nevertheless the remaining generation ofheat the to the idlestate losses in the motor, consisting essentially ofthe core losses of the motor, will be of a magnitudesuch that breakdownof the motor due to overheating would take place if it were allowed togo on running 'WlthOllt being cooled. In addition, even in its idlingstate the frictional losses in motor and pump may be considerablebecause extraneous objects will frequently be wedged between theimpeller and pump casing thus giving rise to a very great frictionalresistance. j 7

Various measures have been proposed with a view to prevent the drivemotor from attaining excessive temperatures on failure of the liquidcooling. Thus it has been proposed to make provision for automaticallyswitching off the current supply to the drive motor whenever itstemperature exceeds a predetermined value. However, such safetyarrangements are inherently complicated and expensive and are liable tofailure as a result of the rough handling to which bilge pumps andsimilar pumps are often subjected in service.

In accordance with this invention the problem of pre- V simpler way.According to the invention the cooling duct system is provided with oneor more passageways leading directly into the ambient atmosphere andcontrolled by valves adapted to remain closed as long as liquid is beingpumped through the cooling duct system and to open automaticallywhenever the liquid flow ceases. After the valve or valves are opened,the centrifugal pump will force a flow of air through the cooling ductsystem and directly back to the ambient atmosphere through the openedpassageways, and this airflow, owing to the comparatively low resistanceto flow, will be sufliciently forceful to be capable of dissipating theheat generated due tothe idlestate losses and thus to prevent the motorfrom reaching an impermissibly high temperature.

The valves controlling the outlet passageways to the ambient atmospheremay be in the form of spring-loaded valves which are maintained in theirclosed position by the liquid pressure against their spring load as longas liquid is flowing through the cooling duct system, and areautomatically urged to their open position by their springs as soon asthe liquid flow ceases.

The invention is applicable with particular advantage to portable bilgepumps having vertical impeller shafts, although it is applicable also toother kinds of liquid pumps in which the liquid pumped is utilized as acoolant for the drive motor.

The invention will now be described more closely in conjunction with theaccompanying drawing, in which:

FIG. 1 is a cross-sectional elevation of a portable bilge pump embodyingthe invention; and

FIG. 2 is a fragmentary view showing a modified form of the valvemechanism. I

Referring to the drawing, numeral 10 designates the liquid-sealinglyenclosed electromotor, being, as a rule, an alternating-current motor,and 11 denotes the extended motor shaft having the impeller 12 keyedthereto. The pump housing, which is composed of an upper cup-shapedmember 13 lined with rubber or similar material and a lower cup-shapedmember 14 also lined with rubber, is bolted to the stator casing of thedrive motor. Designated by 15 is a cylindrical sheet-metal outer casingcoaxially surrounding the enclosed drive motor 10 so as to form betweenthe latter and the outer casing a cooling duct 16 which is annular incross section. Opening into the bottom portion of this duct are thedischarge passages 17 from the centrifugal pump, whereas the outlet hose18 for carrying away the liquid being pump ed is connected to. the upperend portion of the cooling duct. A downward extension of theoutercas-ing 15 constitutes an annular strainer 19. An end plate 20confining a suction chamber 21 between the strainer 19' and the intakeopening of the pump, constitutes a foot for supporting the pump assemblywith its shaft extending vertically on the bottom of the vesselcontaining the body of water to be drained. Numeral 22 designates theelectric connecting cable of the drive motor, and numeral 23 denotes acarrying handle.

The water sucked in through strainer 19 is forced by the impeller 12upward through the annular duct 16 and out through the hose 18. On itspassage through duct 16, the water being pumped cools the electric motor10 whereby the latter is prevented from attaining an impermissibly hightemperature.

In order to ensure continued cooling of the motor 10 in the case offailure of the water flow through the cooling duct 16, there is providedin the wall of the cooling duct, according to the invention, at leastone outlet passageway 24 adapted, during pumping, to remain closed by avalve. As shown in the drawing, the valve comprises a poppet head 25secured, as usual, to a valve stem 26 which is guided for endwisemovement and urged by a spring 27 towards theposition showncorresponding to the open state of the valve. The spring 27 at its outerend abuts a cover 28 having a downwardly facing outlet 29. Upon startingthe pump, the water being pumped will initially be forced out throughthe open passageway 24, 29, but the pressure of the liquid being pumpedwill immediately cause closing of the valve 25 while compressing thespring 27 so that thereafter the whole amount of water being pumped willbe discharged through the hose 18. The water thus flowingthrough theannular duct 16 causes effective cooling of the drive motor 10. If lateron the liquid flow will cease due, for example, to the pump havingdrained oil the water in which itis immersed, then the valve 25 isautomatically returned by the spring 27 into its open position, afterwhich a flow of air will be forced by the impeller 12 through thecooling duct 16 and the" open passageway 24, 29 directly to the ambientatmosphere. The resistance to flow of the cooling duct 16 is now so lowthat the airflow will be sufficiently forceful to be able to causeetfective cooling of the now idling drive motor 10 and of the remainderof the pump assembly.

It is suitable, in order to cause the cooling air to sweep the electricmotor 10 as thoroughly as possible all round,

aoaaaoe uniformly spaced about the circumference. In this way it will beensured also that at least one air outlet will provide an unobstructedpassage to the atmosphere in case the pump assembly should happen tofall over in such a way that the other outlet is obstructed by thebottom of the sump or the like to be drained.

The valve-controlled air outlet passageways need not necessarily beprovided indirect connection with the 0001-. ing duct, as shown in FIG.1, it being possible instead to provide the same in the wall of the hoseconduit 18 at a locality not too distant from the connection of the hoseto the coolingduct system. A suitable construction is shown in FIG. 2.Herein numeral 30 designates a tubular housing integrally formed withhose connecting nipples and assumed to be inserted in the hose 18 ratherclose to its connection to the pump assembly. Formed in the walls of thetubular housing are two diametrically opposite openings 3']. controlled'bydndividual spring loaded poppet va1ves'25'. The outer end of each airoutlet passageway is closed by a cup-shaped member 32 providedcircumferentially with a large number of apertures 33. Whenever the pumpis idling and thus not discharging any liquid through the hose, thevalves 25 ccsageways 31 directly to the ambient atmosphere while Icooling the drive motor. If the pump should again begin to dischargeliquid, the valves 25, will be closed automatically by the action of theliquid pressure, after which the cooling of the motor will take place inthe normal way utilizing the liquid being pumped as a coolant.

Obviously, the invention is applicable not only to watercooled drain or.bilge pumps having vertical impeller shafts, but also to other kinds ofelectromtor-driven liquid pumps in which the liquid displaced isutilized as a coolant for the pump assembly. a

What is claimed is: r I

1. A pump unit comprising, in combination, a cen- 4 trifugal pump, anelectric driving motor for said pump, a cooling duct system in heatexchange relationship with said electric motor, said cooling duct systemhaving an inlet and an outlet, the inlet of said cooling duct systembeing connected to the delivering end of said centrifugal pump and theoutlet thereof being connectible to a discharge conduit, one or morepassageways leading to the ambient atmosphere provided adjacent theoutlet end of said cooling duct system, a valve located in eachpassageway, each valve having means to maintain its assooiatedpassageway closed as long as liquid is being pumped through the coolingduct and to open the passageway automatically whenever the liquid flowceases.

2. A pump assembly according to claim 1 characterized in that therespective valves are arranged to be acted on by springs which urge thevalves towards their open position but allow the valves to be closedunder the action of the liquid pressure upon liquid being pumped throughthe cooling duct system.

3. A pump assembly according to claim 1 in which the cooling duct systemcomprises an annularly crosssectioned cooling duct surrounding the motorand formed between the motor and an outer casing surrounding the same,characterized in that the valve controlled outlet passageways areprovided in the wall of the outer casing, suitably at the end thereofremote from the inlet to the cooling duct.

4. A pump assembly according to claim 1, characterized in that the valvecontrolled outlet passageways are provided in the wall of the dischargeconduit leading from the pump, or cooling duct, and at a slight distancefrom the connection of the hose to the cooling duct.

References Cited in the file of this patent UNITED STATES PATENTS1,625,892 Hollander Apr. 26, 1927 2,325,930 Avigdor Aug. 3, 19432,924,179 Isaksson Feb. 9', 1960

